title: Vendor differences in alcohol consumption and the contribution of dopamine receptors to Pavlovian-conditioned alcohol-seeking in Long-Evans rats.
abstract: BACKGROUND
  Drug-associated environmental stimuli elicit craving in humans and drug-seeking in animals.
  
  
  OBJECTIVE
  We tested the hypothesis that Pavlovian-conditioned alcohol-seeking is mediated by dopamine, using rats from two vendors.
  
  
  METHODS
  Male, Long-Evans rats (220-240 g) from Charles River (St-Constant, QC, Canada) and Harlan Laboratories (Indianapolis, IN, USA) received 21 sessions of intermittent, 24-h access to ethanol (15 %, v/v) and water in the home-cage. Subsequently, rats were trained to discriminate between one conditioned stimulus (CS+) that was paired with ethanol (0.2 ml per CS+) and a second stimulus (CS-) that was not. Entries into a fluid port where ethanol was delivered were recorded. Next, rats were exposed to a different context where cues and ethanol were withheld. At test, responding to the CS+ and CS- without ethanol was assessed in the second, non-alcohol context. Injections (1 ml/kg; s.c.) of the dopamine D1-receptor antagonist SCH 23390 (0, 3.33, and 10 μg/kg) or dopamine D2-receptor antagonist eticlopride (0, 5, and 10 μg/kg) were administered before test.
  
  
  RESULTS
  Home-cage alcohol consumption was higher in Harlan rats than Charles River rats. At test, saline-treated rats responded more to the alcohol-predictive CS+ than the CS-. While SCH 23390 attenuated CS+ responding in rats from both vendors, eticlopride reduced CS+ responding in Harlan rats only. Subsequently, SCH 23390 but not eticlopride attenuated CS+ responding when the CS+ was again paired with ethanol.
  
  
  CONCLUSIONS
  These results indicate important differences in alcohol consumption in Long-Evans rats from different suppliers, and highlight a novel role for dopamine in Pavlovian-conditioned alcohol-seeking.
authors.affiliation: Center for Studies in Behavioral Neurobiology/Groupe de Recherche en Neurobiologie Comportementale, Department of Psychology, Concordia University, 7141 Sherbrooke Street West SP 244, Montreal, QC, H4B-1R6, Canada.
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Sparks
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Sciascia
authors.forename: Ziada
authors.initials: Z
authors.lastname: Ayorech
authors.forename: Nadia
authors.initials: N
authors.lastname: Chaudhri
mesh_terms: D000428:Alcohol Drinking / Q000503:physiopathology*; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D002492:Central Nervous System Depressants / Q000494:pharmacology; D003214:Conditioning, Classical / Q000187:drug effects; D003463:Cues; D004192:Discrimination, Psychological / Q000187:drug effects; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D058999:Drug-Seeking Behavior / Q000502:physiology*; D000431:Ethanol / Q000494:pharmacology; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D011954:Receptors, Dopamine / Q000378:metabolism*; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D012457:Salicylamides / Q000494:pharmacology; D013028:Space Perception / Q000187:drug effects; D013045:Species Specificity; D015430:Weight Gain / Q000187:drug effects
chemical_list: D001552:Benzazepines; D002492:Central Nervous System Depressants; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C534628:SCH 23390; D012457:Salicylamides; D000431:Ethanol; C045989:eticlopride